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How to protect code inside TM4C123x

Vivian(MCU) Zhang
Intellectual 1545 points


Hi,

I serached datasheet that there's no description about how to protect the code inside TM4C123x be read.

For MSP430, we could protect by fusing the JTAG Pins. What about Tiva? Any similar ideal or by other way?

Thanks!

 

Vivian

  • 0
    Guru 117855 points

    The (proper) definition of "protect" bears (somewhat) upon your objective - does it not? 

    You cannot (really) "protect" your past MCU - nor these!

    Instead - you may place obstructions/hurdles in the path of, "amateurs" - but know that a motivated, equipped, "pro" can - rather easily - gain full access to even such "protected" code.

    It's clear you've made little (likely no) effort to "search" this topic before posting.   Issue has been very well covered - right here - very recently...

  • 0
    TI__Guru**** 244400 points
    Hello Vivian,

    There are 2 main methods of protecting code in TM4C12x devices

    1. Configure the JTAG Pins as GPIO by application code
    PRO: Software controlled and can use a switch button press to move back to JTAG mode for debug
    CON: Finite time for which JTAG will be open
    2. Configure the bits 1:0 of BOOTCFG register to 0x0 and commit the BOOTCFG register.
    PRO: The device shall remain locked from start
    CON: Cannot be overridden in software for JTAG open.

    Besides the same the FMPPE and FMPRE also offer some level of code protection like Execute Only preventing a read of the code amongst other options

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Guru 47900 points

    Hi Amit,

    If this TI employee conveys the fact that the code w/in the MCU is, "protected" that may be a grave error - and raise your firm's legal liability.

    "Protect" may be ruled by judge/jury as, "a far higher standard" than a more limited wording - such as, code being "resistant" to such unauthorized access.

    Of course TI legal should guide here - yet I know "protect" - in its normal/customary usage - may well invite trouble...

    Marketing's "reach" may have exceeded "safe & supportable claims" - in the choice of this wording...

  • 0 in reply to cb1
    TI__Guru**** 244400 points
    Hello cb1,

    Not code is protected but access to code is protected.. Thanks for the correction.

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Guru 47900 points

    Sorry but (still) NO!

    Access is made more "Resistant" - use of "Protect" (instead) imparts (usually) far higher standard... (TI Legal - really should decide/guide...)

  • 0 in reply to cb1
    TI__Guru**** 244400 points
    Hello cb1,

    The first two methods described make the access to the code via JTAG protected (the 2nd one more than the 1st one). If the user wishes to access JTAG they must Mass Erase the device which will remove the code as well.

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Guru 47900 points

    Many "wrist-watches" used to boast, "Water Proof."

    Even fine watches today - most always - replace that language with, "Water Resistant."      (there IS justification for such change)

    I've sounded an alert - follow-on actions beyond my control...